De-skew mechanism

ABSTRACT

A de-skew mechanism includes a driving shaft installed on a frame of an image forming device and driven by a motor, an active roller installed on the driving shaft and driven by the driving shaft, and an idle roller driven by the active roller for driving a medium with the active roller. A nip is formed between the active roller and the idle roller. The de-skew mechanism further includes a correcting member installed on the driving shaft in a rotatable manner and located upstream of the nip for correcting skew of the medium in a correcting position, and a restoring member connected to the correcting member for loading torque to the correcting member so as to drive the connecting member from the correcting position to a releasing position where the medium pass therethrough.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a de-skew mechanism, and more particularly, to a de-skew mechanism capable of correcting skew of a medium effectively and without damage.

2. Description of the Prior Art

When printing to paper with a fax machine, a printer, or a multi-function product, a paper-feeding mechanism is utilized for feeding paper one sheet at a time into machines so as to proceed to faxes, printouts, copies, and so on. For preventing skew images on print media, several methods are applied to get rid of skew feed of print media due to skew position or tolerance.

U.S. Pat. No. 6,011,948 discloses a de-skew mechanism applied to an image forming device. Please refer to FIG. 10 and FIG. 11. The de-skew mechanism includes shutter members 15 and a connecting member 16 for connecting the shutter members 15. The de-skew mechanism is installed on a rotary shaft 18 of a conveyer roller 13 in a rotatable manner. An end 24 b of each twisted coil spring 24 is connected to the connecting member 16. A leading edge of a sheet S contacts with a collision surface 20 a of the shutter member 15. The sheet S forms a curved loop when pushing the shutter members 15. The shutter members 15 correct the skewed sheet S after being pushed by the sheet S and rotating at a predetermined angle. When the sheet S passes through rollers, the shutter members 15 restore to initial positions by the twisted coil springs 24. However, when the sheet S passes through the rollers, the shutter members 15 apply improper torque to the sheet S with the twisted coil springs 24 so that the sheet S might be damaged during being conveyed. Besides, the de-skew mechanism installed on the rotary shaft 18 wholly is not capable of correcting skew of the sheet due to assembly tolerance of the rollers. When the leading edge of the sheet S collides with the shutter members 15, it can not correct the skewed sheet effectively as the sheet is conveyed and corrected simultaneously.

SUMMARY OF THE INVENTION

It is therefore a primary objective of the claimed invention to provide a de-skew mechanism capable of correcting skew of a medium effectively and without damage for solving the above-mentioned problem.

According to the claimed invention, a de-skew mechanism includes a driving shaft installed on a frame of an image forming device and driven by a motor, an active roller installed on the driving shaft and driven by the driving shaft, and an idle roller driven by the active roller for driving a medium with the active roller. A nip is formed between the active roller and the idle roller. The de-skew mechanism further includes a correcting member installed on the driving shaft in a rotatable manner and located upstream of the nip for correcting skew of the medium in a correcting position, and a restoring member connected to the correcting member for loading torque to the correcting member so as to drive the connecting member from the correcting position to a releasing position where the medium pass therethrough.

According to the claimed invention, the correcting member includes a connecting portion connected to the restoring member, and a correcting portion for blocking the medium so as to correct the skew of the medium.

According to the claimed invention, the correcting portion is a protrusion.

According to the claimed invention, a surface of the correcting portion for blocking the medium is a plane.

According to the claimed invention, the de-skew mechanism further includes a stopping member for stopping rotation of the restoring member.

According to the claimed invention, the stopping member is a blocker protruding from the frame of the image forming device.

According to the claimed invention, the restoring member is a weight.

According to the claimed invention, the weight is connected with the connecting portion integrally.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a de-skew mechanism according to a preferred embodiment of the present invention.

FIG. 2 is a schematic drawing of the de-skew mechanism according to the preferred embodiment of the present invention.

FIG. 3 is a schematic drawing of a correcting member according to the preferred embodiment of the present invention.

FIG. 4 is a lateral view of the de-skew mechanism according to the preferred embodiment of the present invention.

FIG. 5 to FIG. 9 are lateral views of the de-skew mechanism in different situations according to the preferred embodiment of the present invention.

FIG. 10 is a sectional view of a de-skew mechanism in the prior art.

FIG. 11 is an enlarged view within A1 region in FIG. 10 of the de-skew mechanism in the prior art.

DETAILED DESCRIPTION

Please refer to FIG. 1, FIG. 1 is a diagram of a de-skew mechanism according to a preferred embodiment of the present invention. A pickup roller 230 is disposed on the beginning of a conveying path 243 of a medium M stacked on a tray 210. The pickup roller 230 picks up the medium M from the tray 210 one sheet at a time and conveys the medium M into the conveying path 234. An input roller 220 conveys the medium M in a direction F along the conveying path 243 to an active roller 246 and an idle roller 247, and then a scan module 200 can scan the medium M. At last, an output roller 250 conveys the scanned medium M to the tray 210. An active roller 246, an idle roller 247, and a correcting member 244 connected to the active roller 246 are disposed on the conveying path 243.

Please refer to FIG. 2, FIG. 2 is a schematic drawing of the de-skew mechanism according to the preferred embodiment of the present invention. A driving is installed on a frame of an image forming device, such as a scanner. The active roller 246 is fixed on the driving shaft 245 and driven by a motor (not shown in figures). The idle rollers 247 are disposed below the active roller 246, and a nip is formed between the active roller 246 and the idle roller 247 so as to nip the medium M. The correcting member 244 is installed on the driving shaft 245 in a rotatable manner and located upstream of the nip and outwards the active roller 246.

Please refer to FIG. 3, FIG. 3 is a schematic drawing of the correcting member 244 according to the preferred embodiment of the present invention. A driving shaft 245 is installed on a frame of an image forming device, such as a scanner. The correcting member 244 includes opening 101 for sheathing on the driving shaft 245. The correcting member 244 includes a correcting portion 242, which can be a protrusion, for protruding to the conveying path 243 and located upstream of the nip of the active roller 246 and the idle roller 247. The correcting member 244 further includes a connecting portion 241. The correcting portion 242 located in a correcting position upstream of the nip of the active roller 246 and the idle roller 247 for blocking the medium M so as to correct the skew of the medium M. The correcting portion 242 located in a releasing position where the medium M collides with the correcting portion 242 allows the medium M to pass through the nip of the active roller 246 and the idle roller 247.

Please refer to FIG. 3 and FIG. 4, FIG. 4 is a lateral view of the de-skew mechanism according to the preferred embodiment of the present invention. The de-skew mechanism further includes a restoring member 100, which can be a weight, connected to the connecting portion 241 of the correcting member 244 for loading torque to the correcting member 244 so as to drive the connecting member 244 from the correcting position to the releasing position where the medium M pass therethrough. The restoring member 100 can be connected with the connecting portion 241 integrally or a separate structure from the connecting portion 241. The material and disposition of the restoring member 100 can be designed according to the type of the medium M. The de-skew mechanism further includes a stopping member 111 disposed in the rear of the restoring member 100 and below a frame 214 for stopping rotation of the restoring member 100. The stopping member 111 can be a blocker protruding from the frame 214 of the image forming device.

In this embodiment, a surface of the correcting portion 242 for blocking the medium M can be a plane for contacting with the medium M smoothly so as to correct the skew of the medium M easily.

Please refer to FIG. 5 to FIG. 9, FIG. 5 to FIG. 9 are lateral views of the de-skew mechanism in different situations according to the preferred embodiment of the present invention. An end of a leading edge of the skewed medium M contacts the surface of the correcting portion 242 and is blocked by the correcting portion 242. Afterwards, the other end of the leading edge of the skewed medium M contacts the surface of the correcting portion 242 and is blocked by the correcting portion 242 so that the correcting portion 242 can not rotate when conveying the skewed medium M continuously until force applied for the correcting member 244 by the medium M can overcome the torque loaded by the restoring member 100 and the weight of the correcting member 244.

The medium M driven by the input roller 220 forms a curved loop during the conveying path 243 when pushing the correcting portion 242. Please refer to FIG. 6, when the leading edge of the medium M aligns the surface of the correcting portion 242, the skew of the medium M is corrected completely. When the force applied for the correcting member 244 by the medium M overcomes the torque loaded by the restoring member 100 and the weight of the correcting member 244, it drives the correcting member 244 to rotate and the leading edge of the medium M keeps aligning the surface of the correcting portion 242. The restoring member 100 connected to the correcting member 244 rotates accordingly so that the torque loaded to the correcting member 244 by the restoring member 100 is decreasing due to decrease of a distance between the restoring member 100 and the driving shaft 245 and resistant force applied for the medium M by the correcting portion 242 decreases. Please refer to FIG. 7, the leading edge of the medium M enters the nip of the active roller 246 and the idle roller 247 and is driven by the active roller 246 and the idle roller 247 cooperatively.

Please refer to FIG. 8 and FIG. 9, when the active roller 246 and the idle roller 247 are conveying the medium M out of the nip of the active roller 246 and the idle roller 247 cooperatively, the correcting member 244 rotates from the correcting position to the releasing position. Afterwards, the active roller 246 and the idle roller 247 conveys the deskewed medium M to the scan module 200 cooperatively and the correcting member 244 returns to the correcting position by the restoring member 100.

The torque loaded to the correcting member 244 by the restoring member 100 is increasing due to deviation from the correcting position of the correcting member 244 so that the torque drives the correcting member 244 to rotate from the releasing position to the correcting position for next correction.

When the correcting member 244 rotates from the releasing position to the correcting position, the correcting member 244 might rotate over the original correcting position. For preventing it, the stopping member 111 disposed in the rear of the restoring member 100 is utilized for stopping rotation of the restoring member 100 properly so that the correcting member 244 can return to the correcting position stably.

The de-skew mechanism of the present invention can be utilized in a paper-feeding mechanism of a printer, a fax, a multifunction product (MFP), and so on. The paper-feeding mechanism can be a single paper-feeding mechanism or a duplex paper-feeding mechanism. The medium can be a medium for forming images thereon, such as paper, sheet, a photograph, and so on.

In contrast to the prior art, the de-skew mechanism of the present invention is capable of correcting the skew of the medium effectively as the medium is conveyed and corrected simultaneously. Besides, the de-skew mechanism of the present invention is capable of conveying and correcting the medium without damage.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

1. A de-skew mechanism comprising: a driving shaft installed on a frame of an image forming device and driven by a motor; an active roller installed on the driving shaft and driven by the driving shaft; an idle roller driven by the active roller for driving a medium with the active roller, a nip being formed between the active roller and the idle roller; a correcting member installed on the driving shaft in a rotatable manner and located upstream of the nip for correcting skew of the medium in a correcting position; and a restoring member connected to the correcting member for loading torque to the correcting member so as to drive the connecting member from the correcting position to a releasing position where the medium pass therethrough.
 2. The de-skew mechanism of claim 1 wherein the correcting member comprises a connecting portion connected to the restoring member, and a correcting portion for blocking the medium so as to correct the skew of the medium.
 3. The de-skew mechanism of claim 2 wherein the correcting portion is a protrusion.
 4. The de-skew mechanism of claim 2 wherein a surface of the correcting portion for blocking the medium is a plane.
 5. The de-skew mechanism of claim 1 further comprising a stopping member for stopping rotation of the restoring member.
 6. The de-skew mechanism of claim 5 wherein the stopping member is a blocker protruding from the frame of the image forming device.
 7. The de-skew mechanism of claim 1 wherein the restoring member is a weight.
 8. The de-skew mechanism of claim 2 wherein the restoring member is a weight.
 9. The de-skew mechanism of claim 3 wherein the restoring member is a weight.
 10. The de-skew mechanism of claim 4 wherein the restoring member is a weight.
 11. The de-skew mechanism of claim 5 wherein the restoring member is a weight.
 12. The de-skew mechanism of claim 6 wherein the restoring member is a weight.
 13. The de-skew mechanism of claim 7 wherein the weight is connected with the connecting portion integrally.
 14. The de-skew mechanism of claim 8 wherein the weight is connected with the connecting portion integrally.
 15. The de-skew mechanism of claim 9 wherein the weight is connected with the connecting portion integrally.
 16. The de-skew mechanism of claim 10 wherein the weight is connected with the connecting portion integrally.
 17. The de-skew mechanism of claim 11 wherein the weight is connected with the connecting portion integrally.
 18. The de-skew mechanism of claim 12 wherein the weight is connected with the connecting portion integrally. 